Heat the oven to 300F.,Put the halved tomatoes cut-side up on a baking sheet.,Dry the tomatoes in the oven until shriveled but still juicy, not hard and dry, about 2 hours.,Let cool and then cut into 1/2-inch pieces.,In a medium saucepan, bring the water and stock to a boil.,Remove from the heat and keep covered.,In another medium saucepan, heat the oil over moderate heat.,Add the onion and cook, stirring occasionally, until translucent; about 5 minutes.,Add the barley and stir to coat.,Add about a third of the hot stock mixture and cook at a gentle boil, stirring occasionally, until absorbed.,Add another third of the stock and cook, stirring frequently, until absorbed.,Add the remaining stock and the salt and cook, stirring frequently, until the barley is tender; about 1 hour and 15 minutes total cooking time.,______,Stir the barley vigorously to make the texture creamier.,If it is dry, add more water.,Stir in the butter, Parmesan, cream and three quarters of both the tomatoes and the olives.,Serve the barley risotto topped with the remaining tomatoes and olives.